/**
 * 为轮廓创建边界框（旋转）和椭圆：minAreaRect(), fitEllipse()
 */

#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>

using namespace cv;
using namespace std;

Mat src_gray;
int thresh = 100;
RNG rng(12345);

/// Function header
void thresh_callback(int, void *);

int main(int argc, char *argv[]) {
    /// Load source image and convert it to gray
    CommandLineParser parser(argc, argv, "{@input | stuff.jpg | input image}");
    Mat src = imread(samples::findFile(parser.get<String>("@input")));
    if (src.empty()) {
        cout << "Could not open or find the image!\n" << endl;
        cout << "Usage: " << argv[0] << " <Input image>" << endl;
        return -1;
    }

    /// Convert image to gray and blur it
    cvtColor(src, src_gray, COLOR_BGR2GRAY);
    blur(src_gray, src_gray, Size(3, 3));

    /// Create Window
    const char *source_window = "Source";
    namedWindow(source_window);
    imshow(source_window, src);

    const int max_thresh = 255;
    createTrackbar("Canny thresh:", source_window, &thresh, max_thresh, thresh_callback);
    thresh_callback(0, 0);

    waitKey();
    return 0;
}

/**
 * @function thresh_callback
 */
void thresh_callback(int, void *) {
    /// Detect edges using Canny
    Mat canny_output;
    Canny(src_gray, canny_output, thresh, thresh * 2);
    /// Find contours
    vector<vector<Point> > contours;
    findContours(canny_output, contours, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0));

    /// Find the rotated rectangles and ellipses for each contour
    vector<RotatedRect> minRect(contours.size());
    vector<RotatedRect> minEllipse(contours.size());
    for (size_t i = 0; i < contours.size(); i++) {
        minRect[i] = minAreaRect(contours[i]);
        if (contours[i].size() > 5) {
            minEllipse[i] = fitEllipse(contours[i]);
        }
    }

    /// Draw contours + rotated rects + ellipses
    Mat drawing = Mat::zeros(canny_output.size(), CV_8UC3);
    for (size_t i = 0; i < contours.size(); i++) {
        Scalar color = Scalar(rng.uniform(0, 256), rng.uniform(0, 256), rng.uniform(0, 256));
        // contour
        drawContours(drawing, contours, (int) i, color);
        // ellipse
        ellipse(drawing, minEllipse[i], color, 2);
        // rotated rectangle
        Point2f rect_points[4];
        minRect[i].points(rect_points);
        for (int j = 0; j < 4; j++) {
            line(drawing, rect_points[j], rect_points[(j + 1) % 4], color);
        }
    }

    /// Show in a window
    imshow("Contours", drawing);
}
